Colored encapsulated liquid crystal apparatus using enhanced scattering

Abstract

The present invention relates to use of liquid crystal material encapsulated in a containment medium to produce a controlled colored output, for example, in response to the application, removal and variation in an electric field. In one embodiment a non-pleochroic dye is in the containment medium itself and in another embodiment the non-pleochroic dye is in the liquid crystal material itself; and in both cases the object is to color light. Incident light impinging on the encapsulated liquid crystal material, which is mounted on, in, or with respect to a support medium, is isotropically scattered in the absence of an electric field, and using the principle of total internal reflection (or optical interference or both) a relatively large part of the isotropically scattered light in the support medium is reflected back to illuminate the scattering liquid crystal material, which isotropically scatters such light again, thus increasing the optical path through the dyed material and, therefore, the coloring of the light travelling such increased path. Light scattered back to the viewing direction out of the support medium causes the liquid crystal material to appear relatively bright and colored as compared to the background where there is no liquid crystal material or where the liquid crystal material is in parallel alignment in field-on condition, i.e. aligned with respect to an electric field, and, thus, substantially transmissive. Original incident light where there is no liquid crystal material, that light which is isotropically scattered toward the back or non-viewing side of the display and within a certain cone or solid angle, and that light passing through aligned (field-on) liquid crystal material will tend not to be totally internally reflected; such light will pass through the support medium and may be absorbed by a remote black or colored material. Light amplification type of operation according to another embodiment in which the dye is a fluorescent one that fluoresces, isotropically emitting light in response to incident light (or possibly other radiation).

I claim: 
     
       1. An optical display for displaying a color output, comprising liquid crystal, a non-pleochroic dye, and a containment medium means for containing said liquid crystal in discrete capsule-like volumes, said dye being contained in said containment medium means, said liquid crystal and containment medium means comprising at least one layer of liquid crystal material in a containment medium that tends to distort the natural sturcture of at least some of the liquid crystal material relative to a wall of such containment medium when in the absence of an electric field. 
     
     
       2. The display of claim 1, said dye comprising fluorescent dye. 
     
     
       3. The display of claim 1, said liquid crystal material in a containment medium comprising at least one layer of encapsulated liquid crystal in said containment medium means. 
     
     
       4. The display of claim 1, further comprising a support medium means for supporting said contained liquid crystal, said support medium means being capable of total internal reflection. 
     
     
       5. The display of claim 4, further comprising a further medium means cooperative with said support medium means to form an interface effective to cause such total internal reflection of light impinging on such interface at an angle exceeding a predetermined angle with respect to normal. 
     
     
       6. The display of claim 5, wherein the index of refraction of said support medium means exceeds the index of refraction of said further medium means. 
     
     
       7. The display of claim 6, said further medium comprising a layer of air. 
     
     
       8. The display of claim 4, further comprising a tuned dielectric interference layer of material for effecting selective constructive and destructive interference with respect to light transmitted through a surface of said support medium means. 
     
     
       9. The display of claim 8, said support medium means having a viewing surface through which light may be transmitted in both directions and an opposite surface, and said tuned dielectric interference layer comprising a layer of material on said opposite surface. 
     
     
       10. The display of claim 4, said support medium means having a viewing surface through which light may be transmitted in both directions and an opposite surface, said viewing surface being substantially totally internally reflective as to light in said support medium means impinging thereon at an angle to normal greater than a predetermined magnitude. 
     
     
       11. The display of claim 4, further comprising optical absorbing means for absorbing light transmitted through said support medium means. 
     
     
       12. The display of claim 4, said liquid crystal and containment medium means comprising encapsulated liquid crystal material. 
     
     
       13. The display of claim 1, further comprising means for selectively changing the ordered or random alignment of such liquid crystal to effect, respectively, optical transmission or isotropic scattering of light incident on such liquid crystal. 
     
     
       14. The display of claim 1, wherein said containment medium comprises a water base material, said containment medium tends to align the structure of at least some of the liquid crystal material generally parallel to a wall of the containment medium when in the absence of an electric field, and said dye comprises a water soluble dye. 
     
     
       15. A liquid crystal display comprising liquid crystal means for selectively isotropically scattering light or transmitting light, substantially transparent support medium means for supporting said liquid crystal means, and dye colorant in said support medium means for coloring light isotropically scattered in said support medium means, said support medium means comprising a containment medium means for containing quantities of liquid crystal means in capsule-like environments as encapsulated liquid crystal and support means for supporting said encapsulated liquid crystal. 
     
     
       16. Liquid crystal apparatus comprising liquid crystal means for selectively primarily scattering or transmitting light in response to a prescribed input, a support medium means for holding therein such liquid crystal means, said support medium means having a characteristic of total internal reflection, and dye means in at least one of said liquid crystal means and said support medium means for coloring light transmitted therein, said support medium means comprising a containment medium means for forming with said liquid crystal means encapsulated liquid crystal and a support means for supporting said encapsulated liquid crystal, said support means having a viewing angle and an opposite side, the index of refraction of said support means being greater than the index of refraction of at least one of the media respectively at such viewing and opposite sides forming an interface therewith to effect total internal reflection of light in said support means incident on such interface at an angle exceeding a predetermined cone of light angle at which light would be transmitted through such interface. 
     
     
       17. The apparatus of claim 16, said dye comprising non-pleochroic dye dissolved in said containment medium means. 
     
     
       18. The apparatus of claim 16, said dye comprising non-pleochroic dye dissolved in said liquid crystal means. 
     
     
       19. The apparatus of claim 16, said dye comprising a fluorescent dye. 
     
     
       20. The apparatus of claim 19, said fluorescent dye being non-pleochroic. 
     
     
       21. The apparatus of claim 16, said dye means comprising a water soluble pigmented dye dissolved in said containment medium. 
     
     
       22. The apparatus of claim 16, wherein said viewing side emits light transmitted in said support means to impinge on said viewing side at an angle less than a predetermined angle with respect to normal as colored illumination when said liquid crystal means is in random alignment. 
     
     
       23. The combination of operationally nematic liquid crystal material contained in a generally spherical capsule of encapsulating medium, said encapsulating medium having a wall, the ordinary index of refraction of said liquid crystal material being approximately the same as the index of refraction of the encapsulating medium, and non-pleochroic dye in at least one of said liquid crystal material and encapsulating medium. 
     
     
       24. The combination of claim 23, said containment medium comprising a water base material, and said dye comprising a water soluble dye dissolved in said containment medium. 
     
     
       25. The combination of claim 23, said liquid crystal material comprising an oil base material, and said dye comprising an oil soluble dye dissolved in said liquid crystal material. 
     
     
       26. An optical apparatus for providing a color output comprising an operationally nematic liquid crystal, containment medium means for containing said liquid crystal, support medium means for supporting said containment medium means and liquid crystal, and a non-pleochroic dye, said liquid crystal means having positive dielectric anisotropy and having an ordinary index of refraction substantially matched to that of said containment medium means to maximize optical transmission in the presence of an electric field and to effect scattering in the absence of an electric field. 
     
     
       27. The apparatus of claim 26, wherein the dielectric constant of said support medium means is at least about as large as the lower dielectric constant of said liquid crystal. 
     
     
       28. The apparatus of claim 26, said support medium means having a viewing side and an opposite side, respective media at said viewing and opposite sides, and the index of refraction of said support medium means being greater than the index of refraction of the medium at one of respectively such viewing and opposite sides, and reflecting means for reflecting light and comprising an interface of such one of said sides with the medium thereat to effect total internal reflection of light in said support medium means incident on such interface at an angle exceeding a predetermined cone of light angle at which light would be transmitted through such interface. 
     
     
       29. The apparatus of claim 26, said liquid crystal and said containment means comprising a layer of encapsulated liquid crystal, and further comprising electrode means positioned between said support medium means and said layer of encapsulated liquid crystal for applying an electric field to align said liquid crystal with respect thereto. 
     
     
       30. The apparatus of claim 26, said liquid crystal comprising an emulsion of liquid crystal material and said containment medium means, said liquid crystal material and said containment medium means being operative to effect substantially isotropic scattering in the absence of an electric field. 
     
     
       31. The apparatus of claim 26, further comprising light director means for directing incident light into said support medium means. 
     
     
       32. The apparatus of claim 31, said director means comprising a louvered light control film. 
     
     
       33. The apparatus of claim 31, said director means comprising means for directing such incident light into said support medium means at a direction substantially out of the usual viewing line of sight from said viewing side. 
     
     
       34. The apparatus of claim 26, said support medium means having a viewing side and an opposite side, and further comprising a tuned dielectric interference layer on said opposite side of said support medium means for effecting optical constructive interference of at least some of the light in said support medium means incident on said interference layer or the interface thereof with said support medium means at an angle exceeding a predetermined cone angle and destructive interference of light incident at an angle within such cone angle. 
     
     
       35. The apparatus of claim 26, said liquid crystal and containment medium means comprising an emulsion of said liquid crystal and said containment medium means. 
     
     
       36. The apparatus of claim 35, further comprising additive means in said operationally nematic liquid crystal material for expediting such distorting and return to random alignment upon the removal of such electric field. 
     
     
       37. The appartus of claim 35, said support medium means further comprisng a substantially optically transparent support. 
     
     
       38. The apparatus of claim 37, further comprising electrode means for applying an electric field to said liquid crystal to cause the latter to change from a random alignment condition distorted in configuration or shape by the wall of respective capsule-like volumes in such emulsion for scatterng light incident thereon to generally parallel alignment condition to trasmit light incident thereon. 
     
     
       39. The apparatus of claim 35, further comprising chloroform. 
     
     
       40. The apparatus of claim 35, further comprising a surfactant. 
     
     
       41. The apparatus of claim 40, said surfactant comprising a non-ionic surfactant. 
     
     
       42. The apparatus of claim 35, further comprising an aligning means at least partly reactive with said containment medium means to align in relatively fixed position with respect thereto, and said aligning means being so positioned with respect to walls of volumes formed in said emulsion and with respect to said liquid crystal to align at least part of at least some of the latter substantially normal with respect to said wall. 
     
     
       43. The apparatus of claim 42, said aligning means comprising a chrome alkyl complex. 
     
     
       44. An optical shutter formed of the liquid crystal apparatus of claim 26. 
     
     
       45. A display device formed of the liquid crystal apparatus of claim 26. 
     
     
       46. The display of claim 45, said liquid crystal comprising at least one layer of liquid crystal material in said containment medium means that tends to distort at least some of the liquid crystal material to align generally with respect to a wall of such containment medium means when in the absence of an electric field, and said liquid crystal material being responsive to an electric field to tend to align with respect thereto. 
     
     
       47. A display device formed of a liquid crystal apparatus for providing a color output comprising an operationally nematic liquid crystal in a support medium and a non-pleochroic dye, said liquid crystal comprising at least one layer of liquid crystal material in a containment medium that tends to distort at least some of the liquid crystal to align generally with respect to a wall of such containment medium when in the absence of an electric field, and said liquid crystal being responsive to an electric field to tend to align with respect thereto. 
     
     
       48. An optical device for producing a colored optical output, including a containment medium comprising a non-pleochroic dye means for coloring light and a polymer base, said containment medium having a total internal reflection angle and being operative to effect total internal reflection of light impinging on a surface thereof at an angle exceeding such total internal reflection angle, and liquid crystal material in said containment medium, said liquid crystal material being cooperative with said containment medium in the absence of electric field to scatter a substantial amount of light at an angle greater than the total internal reflection angle for said medium substantially independently of wavelength. 
     
     
       49. The optical device of claim 48, said containment medium comprising means for defining volumes for containing said liquid crystal material therein. 
     
     
       50. The device of claim 49, said support medium further comprising support means for supporting said containment medium and said liquid crystal material. 
     
     
       51. The device of claim 50, wherein the ordinary index of refraction of said liquid crystal material is substantially matched to the index of refraction of said support medium, and the extraordinary index of refraction of said liquid crystal material is different from the index of refraction of said support medium to effect refraction and scattering of light in the absence of an electric field. 
     
     
       52. The device of claim 51, the device having a viewing surface and an opposite surface, and further comprising an optical absorber means positioned beyond said opposite surface of said support medium to absorb light transmitted therethrough. 
     
     
       53. The device of claim 48, wherein the ordinary index of refraction of said liquid crystal material is substantially matched to the index of refraction of said support medium, and the extraordinary index of refraction of said liquid crystal material is different from the index of refraction of said support medium to effect refraction and scattering of light in the absence of an electric field. 
     
     
       54. The device of claim 48, the device having a viewing surface and an opposite surface, and further comprising an optical absorber means positioned beyond said opposite surface of said support medium to absorb light transmitted therethrough. 
     
     
       55. The device of claim 48, wherein said containment medium defines volumes for containing liquid crystal material therein, said volumes having wall means for distorting the natural structure of the liquid crystal material in the absence of a prescribed electric field applied to said liquid crystal material, and further comprising electrode means for applying electric field to liquid crystal material in volumes thereof to effect alignment of such liquid crystal material structure with respect to such field. 
     
     
       56. The device of claim 55, further comprising circuit means for applying electric energy to said electrode means to effect selective application of electric field to said liquid crystal material.